Tom, The Citadels are a huge upgrade from the 436. The fact that you need an amp that can follow a difficult load, (Dynaudio) makes this a no-brainer. I would advise two seperate circuits for AC. Good luck finding a used pair. They are most folks' last amps.
Mark Levinson 436 vs. Theta Citadel monoblocks
I'm thinking about to get either one of these to match Dynaudio S5.4, I know they are both good amps, can't decide which is better for S5.4, I like a slight warm sounding, but still with details, big sound stage, not too forward not too laid back, any members had them before? thanks!